Windows XP features System Restore, a program that allows you to essentially turn back the clock on your computer and restore the settings it had at a previous point. You can use System Restore to go back to a restore point from only a few hours earlier, or you also may use System Restore to take your computer back to its original settings. System Restore is also available in Windows Vista and Windows 7.
Click the "Start" menu and point to "All Programs" when the menu appears.
Point to "Accessories" and then "System Tools." Click "System Restore."
Click "Restore my computer to an earlier time" and then select "Next." The "Select a Restore Point" page will appear.
Use the back arrow on the calendar to go back to the earliest bold-faced date on the calendar. Click on the date. Click "Next."
Click "Next" again when the "Confirm Restore Point Selection" page opens. The computer will automatically shut down and restart.
Click "OK" when the "Restoration Complete" page appears. You now have restored Windows XP to the original settings.